[SOLVED] How do I render a partial of a different format in Rails?

How do I render a partial of a different format in Rails?

I'm trying to generate a JSON response that includes some HTML. Thus, I have /app/views/foo/bar.json.erb:

{
  someKey: 'some value',
  someHTML: "<%= h render(:partial => '/foo/baz') -%>"
}

I want it to render /app/views/foo/_baz.html.erb, but it will only render /app/views/foo/_baz.json.erb. Passing :format => 'html' doesn't help.

Solution

Edit: FYI, this is for older versions of Rails

Building on roninek's response, I've found the best solution to be the following:

in /app/helpers/application.rb:

def with_format(format, &block)
  old_format = @template_format
  @template_format = format
  result = block.call
  @template_format = old_format
  return result
end

In /app/views/foo/bar.json:

<% with_format('html') do %>
  <%= h render(:partial => '/foo/baz') %>
<% end %>

An alternate solution would be to redefine render to accept a :format parameter.

I couldn't get render :file to work with locals and without some path wonkiness.